Jaspal Singh; Kavita Sahu; Sini Kuriakose; Nishant Tripathi; D. K. Avasthi; Satyabrata Mohapatra
Abstract
Nanostructured TiO2 thin films with highly enhanced photocatalytic activity were prepared by atom beam sputtering technique. The effects of thermal annealing on the structural, morphological and photocatalytic properties of TiO2 thin films were investigated using X-ray diffraction, atomic force microscopy, ...
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Nanostructured TiO2 thin films with highly enhanced photocatalytic activity were prepared by atom beam sputtering technique. The effects of thermal annealing on the structural, morphological and photocatalytic properties of TiO2 thin films were investigated using X-ray diffraction, atomic force microscopy, field emission scanning electron microscopy, Raman spectroscopy and UV-visible absorption spectroscopy. X-ray diffraction studies showed that the as-deposited TiO2 thin films made up of anatase TiO2 nanoparticles transformed into anatase/ rutile mixed-phase TiO2 nanoparticles upon annealing. Field emission scanning electron microscopy and atomic force microscopy studies revealed growth of TiO2 nanoparticles from 16 nm to 29 nm upon annealing at 600 o C. The photocatalytic activities of the nanostructured TiO2 thin films were studied by monitoring photocatalytic degradation of methylene blue in water. Our results showed that the as-deposited nanostructured TiO2 thin films exhibited highly enhanced photocatalytic efficiency as compared to the annealed samples. The mechanism underlying the enhanced photocatalytic activity of nanostructured TiO2 thin film is tentatively proposed.
D. K. Avasthi; S. K. Sarkar; A. Tripathi; T. Mukherjee
Abstract
The properties of materials at the nano scale critically depend on their size and shape, thus opening a new exciting area of nanotechnology. Its main thrust is to create novel functional materials with their unique physical, chemical and biological properties. The field of engineering of materials with ...
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The properties of materials at the nano scale critically depend on their size and shape, thus opening a new exciting area of nanotechnology. Its main thrust is to create novel functional materials with their unique physical, chemical and biological properties. The field of engineering of materials with desired properties is seeing a revolution as it becomes feasible to fabricate nanoscale building blocks having precisely controlled size and composition. Ionizing radiation (photon, electron and ion beams) have provided immense possibilities for engineering the desired properties of materials and are now emerging as indispensible tools for mesoscopic structuring [1-5]. The field of materials engineering through nano approach has demonstrated tremendous potential in the development of different types of novel materials with new characteristics and functions. The aim of nano engineering with photon, electron and ion beams is to control the nano scale structure of materials to optimize their properties and functionality.
Hardeep Kumar; L. Olivi;G. Aquilanti; S. Ghosh; P. Srivastava; D. Kabiraj; D. K. Avasthi
Abstract
A series of FeCo-SiO2 granular films of different FeCo atomic concentration (33-54%) have been prepared by fast atom beam sputtering technique and post-annealed in inert (Ar) and reducing (H2) gas environments. Fe and Co K-edge XANES analysis of as-deposited films indicate that both Fe and Co are present ...
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A series of FeCo-SiO2 granular films of different FeCo atomic concentration (33-54%) have been prepared by fast atom beam sputtering technique and post-annealed in inert (Ar) and reducing (H2) gas environments. Fe and Co K-edge XANES analysis of as-deposited films indicate that both Fe and Co are present mainly in their elemental (Fe 0 , Co 0 ) state. A partial oxidation of Fe and Co is observed, as the FeCo alloy content decreases (54 to 33%) due to reduced particle size. XANES/XAFS analysis shows the formation of FeCo alloy with bcc Fe structure in H2 environment annealed films. The XRD and Raman analysis of Ar environment annealed films suggest the formation of Co3O4 and CoFe2O4 phases. The Ar environment is found not to be effective reducing medium to stabilize the FeCo alloy phase, while H2 environment annealing (450-700 o C) leads to formation of bcc FeCo alloy.
Jai Prakash; A. Tripathi; G. B. V. S. Lakshmi; V. Rigato; Jalaj Tripathi; D. K. Avasthi
Abstract
Thin metal films of Ag (~10 nm) deposited on spin coated PVC film on quartz substrate, were irradiated with 150 keV Ar ions at fluences varying from 5×10 15 to 5×10 16 ions/cm 2 and characterized with Rutherford backscattering spectrometry (RBS), atomic force microscopy (AFM), scanning electron ...
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Thin metal films of Ag (~10 nm) deposited on spin coated PVC film on quartz substrate, were irradiated with 150 keV Ar ions at fluences varying from 5×10 15 to 5×10 16 ions/cm 2 and characterized with Rutherford backscattering spectrometry (RBS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) techniques. RBS spectra show sputtering of the Ag film. As a result of ion irradiation, isolated Ag nanoparticles are formed on the surface. The size and size distribution of Ag nanoparticles are found to be dependent on ion fluence. Contact angle measurements were carried out to study the hydrophilic nature of the surface at varying fluences. Results are explained in the framework of sputtering from the surface due to dense collision cascade resulting from Ar ion and Ag/PVC film interaction.
R. Singhal; A. Tripathi; D. K. Avasthi
Abstract
Electrically conducting carbon nanowires, all parallel to each other and embedded in fullerene C70 matrix are created by swift heavy ion irradiation of thin fullerene C70 film at low fluences (up to 10 10 ions/cm 2 ). The conductivity of the wires is several orders of magnitude higher than the surrounding ...
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Electrically conducting carbon nanowires, all parallel to each other and embedded in fullerene C70 matrix are created by swift heavy ion irradiation of thin fullerene C70 film at low fluences (up to 10 10 ions/cm 2 ). The conductivity of the wires is several orders of magnitude higher than the surrounding material and it is due to the transformation of fullerene into amorphous carbon within each ion hit zone. These conducting nanowires are evidenced by conducting atomic force microscopy. The typical diameter of the conducting tracks is observed to be about 11-21 nm.
Y. K. Mishra; S. Mohapatra; D. K. Avasthi; N. P. Lalla; Ajay Gupta
Abstract
Au nanoparticles (NPs) embedded in silica matrix were synthesized by atom beam co-sputtering and investigated in detail by transmission electron microscopy (TEM). A study on electron beam induced tailoring of size of Au nanoparticles has been performed in an in-situ TEM experiment as a function of electron ...
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Au nanoparticles (NPs) embedded in silica matrix were synthesized by atom beam co-sputtering and investigated in detail by transmission electron microscopy (TEM). A study on electron beam induced tailoring of size of Au nanoparticles has been performed in an in-situ TEM experiment as a function of electron irradiation time. This study concludes that electron beam irradiation can result in a controlled growth of NPs in proportion to irradiation fluence. Analytical calculations for electron energy loss in Au NPs and fused silica have been performed, which indicate that the observed growth of Au NPs in present case is due to rise in temperature of Au NPs and surrounding silica.
